The present invention relates to a pick-up tube which extends into an oil supply gallery in an engine block to speed the supply of oil to a hydraulically-actuated valve deactivation system to prevent delay of valve deactivation after engine start-up.
Valve deactivation is used for improving fuel efficiency in engines. Valve deactivation cuts off one-half of the available cylinders by deactivating valve lift in those cylinders so that such cylinders remain closed after a combustion cycle of the engine and the burnt gases remain trapped within the cylinder during deactivation.
Some valve deactivators are used in internal combustion engines having a push rod-type valve gear train in which there is a rocker arm, with one end of the rocker arm engaging a push rod and the other end engaging the engine poppet valve. Typically, a central portion of the rocker arm is fixed relative to the cylinder head by a fulcrum arrangement in which the fulcrum normally prevents movement of the central portion of the rocker arm in an xe2x80x9cup and downxe2x80x9d direction. At the same time, the fulcrum permits the rocker arm to engage in cyclical, pivotal movement, in response to the cyclical motion of the push rod, which results from the engagement of the push rod with the lobes of the rotating camshaft.
There are a number of known valve deactivator assemblies which are operably associated with the fulcrum portion of the rocker arm and which, in the latched condition, restrain the fulcrum portion of the rocker arm to move in its normal cyclical, pivotal movement. However, in an unlatched condition, the valve deactivator assembly permits the fulcrum portion of the rocker arm to engage in xe2x80x9clost motionxe2x80x9d such that the cyclical, pivotal movement of the push rod causes the rocker arm to undergo cyclical, pivotal movement about the end which is in engagement with the engine poppet valve. In other words, the rocker arm merely pivots, but the engine poppet valve does not move and therefore is in its deactivated condition.
U.S. Pat. No. 6,196,175 discloses a valve deactivator which is incorporated into a cam follower assembly and is hydraulically-actuated. This device includes an outer body member which engages and follows the cam and an inner body member disposed within the outer body member and reciprocable relative thereto. The inner body member includes means for transmitting the cyclical motion of the cam to the remainder of the valve gear means when the outer and inner body members are in a latched condition. A latch assembly is positioned within the inner body member when in the unlatched condition and includes a radially movable latch member. A source of pressurized fluid, such as oil, is operatively associated with the latch assembly and is operative to bias the latch member toward the unlatched condition.
A hydraulically-actuated valve deactivator, such as that described in the ""175 patent, requires pressurized oil for operation. Such pressurized oil may be received from the engine block. When the engine is first started up, oil galleries of the engine block which might supply such oil would initially be filled with air. However, a solid column of oil would be required to initiate the hydraulically-actuated valve deactivator. Accordingly, cylinder deactivation is delayed until the hydraulically-actuated valve deactivator receives an air-free, pressurized supply of oil. Accordingly, it is desirable to decrease the time between engine start-up and supply of a solid column of oil to the valve deactivator.
The present invention overcomes the above-referenced shortcomings of prior art hydraulically-actuated valve deactivation systems by providing a pick-up tube which extends sufficiently into an oil supply gallery to prevent delay in the supply of a solid (i.e., air-free) column of oil to the hydraulically-actuated valve deactivation system.
More specifically, the present invention provides an engine assembly including an engine block with a laterally extending oil supply gallery formed therethrough. The engine block also includes an aperture formed in fluid communication with the oil supply gallery. A hydraulically-actuated valve deactivation system is positioned in fluid communication with the aperture for receiving pressurized oil from the oil supply gallery. A pick-up tube is positioned within the aperture and has a distal end protruding vertically downward into the oil supply gallery to minimize the amount of air in the oil which is communicated to the hydraulically-actuated valve deactivation system, thereby preventing delay of valve deactivation after engine start-up as oil fills the oil supply gallery and displaces any air from the oil supply gallery.
Another aspect of the invention provides a method of preventing delay in operation of a hydraulically-actuated valve deactivation system after start-up of an internal combustion engine. The method includes the step of providing a pick-up tube as described above which protrudes sufficiently into the oil supply gallery to enhance transfer of pressurized oil from the oil supply gallery into the hydraulically-actuated valve deactivation system after engine start-up to prevent delay of valve deactivation.
Accordingly, an object of the invention is to provide an improved valve deactivation system in which valve deactivation is available more quickly after engine start-up.
The above object and other objects, features and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.